Chromium plating of type



Patented Oct. 30, 1934 CHBOMIUM PLATING OF TYPE Philip 1'. Hale, Toledo,Ohio No Drawing. Application November 21, 1932, Serial No. 643,797

13 Claims.

The main objects of this invention are: First to provide a method forthe direct electrodeposition of chromium on type metal.

Second, to provide type and/or type plates having an exceptionally longlife and improved printing characteristics.

Third, to provide a method of satisfactorily electroplating an alloycontaining a predominant amount of lead with chromium.

Fourth, to provide a method of and means for rejuvenating worn type andtype plates, whereby they are given a new substantially permanentprinting face having improved printing properties.

Objects relating to details and economies of my invention will appearfrom the description to follow. The invention is defined and pointed outin the claims.

Type and type plates are made of an alloy which is generally designatedas type metal. Type metal consists essentially of lead as a base metal,which is alloyed w.th varying amounts of tin and antimony generally,although in some cases, various other metals, such as zinc, copper andiron, are added to the composition of the alloy. The following is an oldrecipe for type metal: 61.3 lb. leads, 20.7 lb. tin, and 18.5 lb.antimony.

For good wear and good printing results, the face of the type should behard and of good depth or clear cut. In use, the type face becomesshallow and finally must be discarded and recast. The same is true oftype plates of type metal and of copper backed by type metal. Theprocessing of a copper electrotype printing plate requires approximately14 hours for the electrodeposition of the copper. Electrotype platesplated with copper are subject to rapid deterioration in use, due to therelatively soft copper face and the type metal back .ng commonly used.Conventional type and type plates of type metal also wear high points ofmetal, which is highly desirable,

away quickly.

Chromium is very hard, wears well and is not subject to corrosion. Itsuse as a face for type and type plates greatly prolongs their life andimproves the character of the printing. However, the chromium plating oftype metals has never before been successfully accomplished, because ofdifiiculty in making the chromium plating adhere to the type metal.Attempts have been made in the past to accomplish this by the use ofinterposed coatings of metals such as copper and/or nickel, but suchprocesses areexpensive.

I have discovered a process of electrodepositing chromium directly ontyp metal without the 55 aid of interposed coatings of metals, such as 0per and/or nickel. The chromium printing face thereon increases the lifeof the type and printing plates from three to fifteen times and alsoresults in improved work. According to my method, the time required forthe chromium electroplating op- 00 eration is approximately only onehour. This results in a time saving of 13 hours over the prior copperelectroplating process. The life of a chromium plated printing plate isa minimum of three times that of a combination; copper and type metalprinting plate and ten to fifteen times that of type metal alone. It isthus seen that the chromium plated plates last-longer and cost less tomanufacture than combination copper and type metal plates.

My method contemplates the use of any standard chromic acid platingbath. If the printing plate has been used, the ink is removed from theplate by the use of an ink remover such as benzine. The plate is thendry polished with whiting, or some other soft slightly abrasive powder,using a. soft cloth or brush, or by a mechanical method such asblasting, which leaves a positively dry polished surface. The plate isthereupon immediately immersed in the electroplating bath and allowed toremain until it reaches the temperature of the bath, approximately 140F. The plate is then connected in electrical circuit with a currentsource and the anode. The voltage is preferably substantially 3.8 voltswith the anode spaced approximately one inch from the cathode, althoughit is possible to use as low as 3.5 volts and as high as 4.2 volts forsatisfactory results. These conditions may be simulated by varying thevoltage and the anode spacing. The electrodeposition is allowed tocontinue for about one hour, at the end of which time the plate isprovided with a clear and deep chromium face which is bright, hard,tough and durable.

The chromium tends to concentrate on the but sufficient chromium isdeposited in the depressed portions so that the type does not have atendency to take up and become compacted with ink. The life of the plateis renewed and prolonged and the character of the printing is greatlyimproved.

In preparing the plate for the bath, I prefer to use a dry polish,inasmuch as as it is safe, produces a high percentage of good work andprovides a good adherency. However, as a substitute, the plate is dippedin a solution of acid or alkali which will not excessively etch oroxidize the type metal.-

1; have described my improvements in an em- 110 bodiment which I havefound very practical. I have not attempted to describe other embodimentsor adaptations, as it is believed this disclosure will enablethoseskilled in the art to. embody or adapt my improvements as may bedesired. 7

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. The process of electrodepositing chromium directly, on a cathodeconsisting of type metal platewith a standard chromic acid bath, whichcomprises cleaning ink from the plate with benzine or the like, drypolishing the printing face with whiting or other soft slightly abrasivepowder using a soft cloth or brush which leaves a positively drypolished surface, immersing the plate in the bath and allowing it toreach the temperature thereof, and connecting the plate in circuit witha current source and the anode, the voltage being 3.3 volts with ananode spacing of one inch or under similar conditions of varying voltageand anode spacing, the voltage being proportional to the anode spacing.

2. The process of electrodepositing chromium directly on a cathodeconsisting of type metal plate with a chromic acid bath, which comprisescleaning the plate, dry polishing the printing face with soft slightlyabrasive powder using a soft cloth which leaves a dry polished surface,immersing the plate in the bath and allowing it to reach the temperaturethereof, and connecting the plate in circuit with a current source andthe anode, the voltage being between 3.5 and 4.2 volts with an anodespacing of one inch.

3. The process of electrodepositing chromium directly on a cathode oftype metal with a standard chromic acid bath, which comprises polishingthe face of the type metal cathode until dry and clean, immersing thecathode in the bath and allowing it to reach the temperature thereof,and connecting the cathode to a current source and the anode, the ratioof voltage to anode spacing being substantially 3.8 volts to one inch ofanode spacing.

4. The process of electrodepositing chromium directly on a cathode oftype metal with a chromic acid bath, which comprises polishing the faceof the type metal cathode until dry and clean, immersing the cathode inthe bath and allowing it to reach the temperature thereof,

and connecting the cathode to a current source and the anode, theanode-cathode spacing being between 3.5 and 4.2 volts per inch.

5. The process of electrodepositing chromium directly on a cathodeconsisting of an alloy containing a predominant amount of lead with astandard chromic acid bath, which comprises dry' polishing the surfaceof the cathode to be plated, immersing the cathode in the bath, andpassing a current from the anode to the cathode, the ratio of voltage toanode spacing being substantially 3.8 volts to one inch.

6. The process of electrodepositing chromium directly on a cathodeconsisting of an alloy containing a predominant amount of lead with achromic acid bath, which comprises dry polishing the surface of thecathode to be plated, immersing the cathode in the bath, and passing acurrent from the anode to the cathode, the anodecathode spacing beingbetween 3.5 and 4.2 volts per inch.

7. The process of rejuvenating the face of used type, which comprisescleaning and dry polishing said face, immersing the type face in astandard chromic acid electrolyte, allowing the type to reach thetemperature of the bath, and connecting said type to a source of currentand anode, whereby chromium is electrodeposited on said face, thevoltage of the current in volts being 3.8 with an anode spacing of oneinch.

8. The process of rejuvenating the face of used type, which comprisescleaning and dry polishing said face, immersing the type face in achromic acid electrolyte, allowing the type to reach the temperature ofthe bath, and connecting said type to a source of current and anode,whereby chromium is electrodeposited on said face, the

anode-cathode spacing being between 3.5 and 4.2 volts per inch.

9. Themethod of electrodepositing chromium directly on a cathodeconsisting of a printing plate of type metal with a chromic acid bath,which comprises cleaning and drying the face of said plate, immersing itin the bath, and when the bath and plate have reached the sametemperature connecting said plate in electric circuit relation with theanode and a current source for substantially one hour, the ratio ofvoltage in volts to anode spacing in inches being substantially 3.8 to1.

10. The method of electrodepositing chromium directly on a cathodeconsisting of a printing plate of type metal with a chromic acid bath,which comprises cleaning and drying the face of said plate, immersing itin the bath, and when the bath and plate have reached the sametemperature connecting said plate in electric circuit relation with theanode and a current source, the ratio of voltage in volts to anodespacing in inches being substantially 3.8 to 1.

11. The method of electrodepositing chromium directly on a cathodeconsisting of a printing plate of type metal with a chromic acid bath,which comprises cleaning and drying the face of said plate, immersing itin the bath, and connecting said plate in electric circuit relation withthe anode and a current source, the ratio of voltage in volts to anodespacing in inches being substantially 3.8 to 1.

12. The process of chromium plating type metal, which comprises cleaningand drying the type metal, maintaining the type metal dry, immersing thedry type metal in a bath of chromic acid, spacing an anode approximatelyone inch from said type metal, and passing a current through the bath ata potential of between 3.5 and 4.2 volts.

13. In the art of electroplating type metal and the like directly withchromium in a bath of chromic acid, the steps which comprisethoroughly'drying the cathode, and immersing it in the oath'while dry,the anode being spaced substantially one inch from the cathode in thebath for a current at a potential of between 3.5 and 4.2

